US 3037244 A
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Description (OCR text may contain errors)
June 5, 1962' H. D. BOGGs APPARATUS FOR CASTING oF TUBULAR ARTICLES Filed Jan. 2l, 1954' I INVENTOR HERBERT D. 50665 United States atnt 3,037,244 Patented June 5, 1962 -1 tlc,
This invention relates to an apparatus for, and a process of, manufacturing ibrously reinforced plastic piping or tubing. More particularly, this invention relates to an improved apparatus and process for molding a pipe by the impregnation of a fibrous reinforcing lining with a liquid settable material such as a thermosetting plastic.
In -my copending applications Serial No. 200,193, filed December 1l, 1950, now U.S. Patent No. 2,776,450, and Serial No. 264,976, tiled January 4, 1952, U. S. Patent No. 2,785,442, assigned to the assignee of the present invention, I have disclosed various methods and apparatus for the formation of iibrously reinforced thermosetting plastic piping. In the co-pending application of Herbert D. Boggs, executed on January 18, 1954, and filed on January 2l, 1954, Serial No. 406,823, assigned as above, now U.S. Patent No. 2,912,041, the preforming of tubular fibrous formations for subsequent insertion within a plastic piping mold is disclosed. In accordance with the present invention, tubular fibrous reinforcing formations of the various types mentioned in said application may be inserted within a mold apparatus which is pecularly adapted to fully utilize the advantages of the preparation and preforming of these tubular fibrous formations. However, the invention is not limited to the utilization of such preformed tubular brous formation, and any fibrous formation including mats, continuously wound sheets, and woven or braided formation, may be used to form the fibrous reinforcement for the impregnated plastic pipe being molded.
It is therefore an object of this invention to provide a process for the formation of brously reinforced plastic pipe.
It is a further object of this invention to provide appa- -ratus for the formation of tlbrously reinforced plastic pipe.
These and other objects of my invention will be fully understood from the following detailed description of a typical preferred form and application of the invention, throughout which description reference is made to the accompanying drawings, in which:
FIGURE 1 is an elevational View of the mold with the mandrel partially inserted therein.
FIGURE 2 is an elevational view, taken in section, of the mold with the mandrel partially inserted therein.
FIGURE 3 is an elevational view, taken in section, of the mold with the mandrel completely inserted therein.
FIGURE 4 is a section taken along line 4 4 of FIG- URE 1.
FIGURE 5 is a section taken along line 5 5 of FIG- URE l; and
FIGURE 6 is a perspective view of a tubular fibrous formation such as is disposed upon a mandrel in accordance with this invention.
Referring to FIGURE l, there is shown generally a tubular vertically disposed mold 10 provided with top ange 12 and -bottom flange 14. Each 0f these llanges is provided with a suitable number of ordinary draw bolts 16 and 17, respectively extending therethrough for use in sealing the flanges in the conventional manner. As shown in FIGURE 2, the mold is hollow and has open ends, and the top end has its flange conically counterbored at 18 to provide a tapered seat which will be discussed hereinafter.
r[here is also provided a hollow mandrel generally indicated at 20 having the lower end closed as at 22 and the top end .sealed by plate 24. The top of the mandrel is provided with an exteriorly disposed peripheral flange 26 `with its underside turned down to provide a conical section 28 having a taper complementary with that of counterbored seat 18. The mandrel Ztl has an exterior diameter somewhat smaller than the interior diameter of the mold 10 `so that when the mandrel is inserted within the mold, the two members will dene an annular cavity or compartment 30 which may be utilized as a molding chamber as will be discussed hereinafter.
In accordance with this invention, a tubular brous formation, for example, a braided fiber glass sleeve 32, as shown in FIG. 6, or `a plurality of concentric ber glass sleeves, is `disposed upon the mandrel Z0, and the mandrel is lthen lowered by means of suspension line 34 into the mold 10. As shown in FIGURE l, the mandrel is somewhat longer than the mold 10 so that While the mandrel is only partially inserted into the mold 10, its lower portion will project from the lower end of the latter.
A `sliding flange 36 may be slid over the exposed lower end of mandrel 20 as shown in FIGURE 1 and then drawn tight to flange 14 by means of draw bolts 17. vFlange ring 36 has an exterior diameter substantially equal to that of lower mold flange 14 and is provided with a plurality of threaded -apertures adapted to be disposed in registry with, and to receive, the draw bolts 16 and 17. The upper surface of the ring flange is counterbored so that a portion of its interior diameter is substantially equal to the interior diameter of the mold 10 )and another portion has a diameter only slightly greater than that of the mandrel 20. The latter portion of the ring flange has its internal periphery provided with an O-ring seal 39 (FIG. 2) which is `adapted to make a sliding seal with the exterior of the mandrel 20.
Referring to FIGURES 1 and 2, the ring flange 36 is provided with a radial port 35 connecting its outer periphery with the counterbored interior periphery. A flexible tubing 33 carrying valve cock 37 and pressure gauge 40 is connected with port 35 and also with a supply of resinous thermosetting liquid.
The mandrel is lowered until its conical shoulder 28 is almost seated within the counterbored seat 18 of the mold 10, at lwhich point the fibrous sleeve 32 will be entirely enclosed within the mold 1l), as shown in FIG. 2. The mandrel is held in this unseated position while the compartment 30 is pumped full of a liquid thermosetting resinous solution, such as urea formaldehyde or phenol formaldehyde. This resinous material is added rather slowly so that the porous interior of the fiber sleeve 30 will be completely permeated and saturated by the Solution. Stated otherwise, the resinous material is added slowly so that all air entrained in the porous ber sleeve can escape upwardly and out of the mold through the annular opening defined by the ange 12 and the conical section 28 of flange 26. The upper mandrel llange 26 may 'be then drawn into a tightly sealed connection with upper mold flange 12 by means of the draw bolts d6', 17. The plastic solution is subjected to a high pressure, for example, 200 pounds per square inch, by any suitable pressurizing means (not shown). Upon the stabilization of such a pressure within the chamber 30, as indicated by pressure gauges 40, valve 37 may be closed to confine and hold this pressure.
The brous reinforced plastic piping within the mold is then cured by the application of suitable quantums of heat for a period which will vary with the particular resinous plastic selected. The curing heat is applied by the introduction of steam into the exterior heating coils 42 disposed about the mold 10, and further by the introduction of steam through conduit '44 which extends into the interior of the mold through the sealed top 24. Steam exit pipe 46 is also provided to communicate with the interior of the mandrel through its top 24. Conduits 44 and 46 may be connected with `any suitable flexible steam conducting tubes 48.
The foregoing description of the use of thermosetting material is only exemplary. The invention also embraces the use of thermoplastic material, With the necessary use of cooling uid rather than steam or other heating medium, to permit initial flow and then setting of the thermoplastic material, such as a polyester resin.
Having described only a typical preferred form and application of the invention, it is not to be limited or restricted to specific details herein `set forth, but I wish to reserve to myself any variations or modifications that may appear to those skilled in the art and falling within the scope of the following claims.
1. Apparatus for molding a iibrously reinforced thermoset plastic pipe comprising; a mandrel, a flange ixed on iirst end of said mandrel, a flange disposed on the second end of said mandrel, a mold receiving said mandrel, means for sealing said first mandrel flange to a first end of said mold, means for sealing said second mandrel tiange to a second end of said mold, and a conduit means in said second mentioned flange for introducing a plastic solution into said mold when said ends are respectively mutually sealed and means for maintaining said plastic solution under pressure.
2. In the apparatus dened in claim 1, heating means on said mold and heating means on said mandrel.
3. In the apparatus defined in claim 1, said first end of said mold `being conically counterbored, said first end of said mandrel carrying a conical collar adapted to be received by said counterbored end of said mold.
4. In the apparatus defined in claim 2, said first end of said mold being conically counterbored, said first end of said mandrel carrying a conical collar adapted to be received by Isaid counterbored end of said mold.
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